Mulling apparatus



Octl 31, 1939. Y y w.F. PIPER y 2,177.945

'MULLING APPARATUS Filed sept. 19, 1936 2 sheets-sheet 2 patented 31,1939 `2,177,945

UNITED STATES PATENT oFFlcE MULLING APPARATUS Walter F. Piper, `Oak Park, Ill., assignor to The Beardsley & Piper Company Chicago, Ill., a corporation of Illinois Application September 19, 1936, Serial No. 101,555

7 Claims. '(Cl. 83-45) The present'invention relates generally to apfiled by me September 14, 1936, Serial No. 100,630. paratus for mulling or mixing granular material. Other objects of the invention and the various More particularly the linvention relates to that advantages and characteristics of the present type of mulling apparatus which is adapted to sand mulling apparatus will be apparent from a mull, mix or recondition molding sand and comconsideration of the Yfollowing detailed descripprises as the main parts or elements thereof tion. d

(1) a frame; (2) an open top sand retaining re- The invention consists in the several novel feaceptacle which is mounted on and supported by tures which are hereinafter set forth and are the frame and embodies a substantially flat cirmore particularly defined by claims at the conm cular bottom and an outwardly bulged side wall cluson hereof. l0 which is -of substantially semicircular cross- In the drawings which accompany and form a section and is joined to and extends upwardly i part of this specification or disclosure and in from the outer margin of the bottom; (3) a pluwhich like numerals of reference denote corre- I rality of rotary balls `which are arranged to travel Asponding parts throughout theseveral Views:

13 in a circular course over the bottom and around Figure 1 is a View partly in plan and partly in 15 `the side wall of the receptacle and are adapted horizontal section of a mulling apparatus emduring such travel to spin and effect the desired bodying the invention; and v mulling, mixing or reconditioning of the sand on Figure 2 is a vertical longitudinal section the receptacle bottom and between them and the .taken on the line 2--2` of Figurel and showing in outwardly bulged side Wall; and (4) a motor and detail the construction and character of the 20 speed reducing gearing for propelling the balls in motor for driving the mulling balls and also the the aforementioned circular course. mechanism or means for revolving or driving the One object of the .invention is to provide a receptacle from the motor. mulling apparatus of this type in which the re- The apparatus which is shown in the drawings ceptacle is mounted to rotate or revolve about a constitutes the preferred embodiment of the ing5 Vertical axis and is driven during operation of the Velitien- It iS designed fOr 115e in 9 foundry 01' apparatus so that the sand on the central pcrlike establishment for mulling, mixing or recondition of the bottom thereof is flung outwardly by tioning molding sand and comprises a frame 3, `centrifugal force into a position wherein it covers a sand holding or retaining receptacle 4, and a the outer marginalportion of the bottom and the pair of mulling balls 5. d 30 inner face of theoutwardly bulbed side wall and The frame 3 Serves aS the SUDDOIE medium is disposed directly in the path of the mulling for the receptacle 4. It is preferably formed of balls. i i cast metal andconsists of a bottom wall 6, a

Another object of the invention is to provide a continuous side wall 1, and a top 8. The bottom mulling apparatus of the last mentioned type wall 6 is designed to rest on the floor of the and character in which the receptacle is driven foundry in which the apparatus is used and toin a novel manner by the motor forpropelling gethe'r with the continuous side wall 'l and the the bans over the bottom and around the side top 8 forms a gear compartmentil. The Side Wall wall of the receptacle. 1, as shown in Figure 2, is formed integrally with 40 A further object of the invention is to provide and extends upwardly from the margin of the o a mulling apparatus of the type and character bottom wall4 6 and embodies an integral outunder consideration which comprises scraper type turned flange l0 at its upper margin. The 110D plows behind the mulling balls for scraping the 8 is similar in size and shape to the bottom wall mulled sand from Vthe side Wall of the receptacle 6. It serves as a closure for the upper portion of and deflecting it inwards toward the central porthe gear compartment 9 and is removably se- 4,5 tion of the receptacle bottom so that it is moved cured to the out-turned flange I0 of the upper outwards by centrifugal force and aeration and a margin of the side l by means of bolts Il. secondary mulling thereof are thus effected. The sand holding `or retaining receptacle 4 A still further object of the invention is to is Positioned Over the top 8 Of the frame 3 and provide a sand mulling apparatus which is consists of a flat bottom I2, an annular side wall 50 generally of new and improved construction and I3, and an upstanding tubular member I4. The not only is extremely efficient in operation but bottom is circular and overlies and is spaced a. embodies certain features and advantages over slight distance above the top 8 of the frame 3. the apparatus which forms the subject matter of The side wall I3 of the receptacle is substantially `an application for United States Letters Patent semicircular in cross-section `and joins the top u face of the receptacle bottom I2 in a gradual curve. The cross-sectional diameter of the side wall is slightly greater than the diameter of the mulling balls 5. The upper margin of the side wall of the receptacle is flared outwards and forms a funnel-shaped mouth I which serves` to receive sand and direct it into the receptacle for mulling purposes. The tubular member I4 is centrally disposed with respect to the side wall I3 and is formed integrally with the bottom I2. The upper end of the member I4 terminates a slight distance above the mouth I5 and the central portion of the member is flared and embodies a substantially quadrantally curved outer surface I6 which joins the top face of the receptacle bottom and serves to direct the sand which is introduced into the receptacle outwardly over the receptacle bottom. The lower end of the tubular member I4 projects beneath the receptacle bottom I2. It extends into a conical depression or socket I1 in the top 8 of the frame 3 and is supported by a roller bearing I8 and a ball bearing I8 in such manner that the receptacle is revolvable about the axis thereof. The socket I1 is defined by means of a downwardly and inwardly extending cone-shaped wall 20 which is formed integrally with the frame top 8 and projects into the gear compartment 9. The roller bearing I8 consists of an inner race 2l, an outer race 22, and an annular series of tapered rollers 23 between the two races. The race 2| surrounds the lower end of. the tubular member I4 of the receptacle and is secured in place by means of a screw thread connection ZIB. The outer race 22 surrounds the inner race and ts within an annular groove in the upper face, of the cone-shaped wall 20. The races 2I and 22 and the rollers 23 are so arranged and constructed that the roller bearing I8 serves not only as a journal for the lower end of the tubular member I4 of the receptacle but also to prevent downward movement or displacement of the receptacle with respect to the frame. The ball bearing I9 is positioned beneath the roller bearing I8 and operates to prevent sidewise displacement or tilting movement of the receptacle. It surrounds the lower end of the tubular member I4 of the frame and consists of an inner race 24, an outer race 25, and an annular series of. balls 26 between the two races. The inner race is in the form of a ring and is disposed in an annular groove 21 in the lower end of the tubular member I4. The outer race 25 surrounds and vis spaced from the inner race and fits within an annular groove within the lower end of the coneshaped wall 20. The balls 26 fit between the inner and outer races of the bearing I9 and coact with such races to form a journal for the lower end of the member I4. The roller bearing I8 and the ball bearing I8 constitute simple means for revolvably supporting the receptacle from and over the frame 3.

The mulling balls 5 are preferably two in number. They comprise metallic cores 28 and solid rubber coverings 2S and are mounted on the lower ends of a pair of substantially vertically extending shafts 38. The shafts, as shown in the drawings, extend through the cores 28 ofthe balls and have at their lower ends nuts 3I which engage the bottom portions of the cores 28 and prevent downward movement of the balls with respect to the shafts. The upper ends of the shafts are connected by roller bearings 32 to a pair of brackets 33 which, as shown in Figure 2, are pivotally connected by horizontally extending pins the forks 4I.

34 tothe outer ends of a cross-arm 35 so that they, together with the shafts and mulling balls, are free to swing radially with respect to the sand holding or retaining receptacle 4. The cross-arm 35 is xedly connected, as hereinafter described, to the upper end of a vertically extending shaft 36 which extends through the tubular member I4 of the receptacle 4 and is driven, as hereinafter described, so as to cause the balls 5 to swing in a circular course around the outwardly bulged side wall I3 of the receptacle. The roller bearings 32 are disposed in cylindrical sockets 31 in the brackets 33 and permit the shafts 30 to rotate about their own axes. As a result of this arrangement the mulling' balls are free to spin or rotate during travel around the side wall of the receptacle. The bearings consist of upper sections 32* and lower sections 32h. The upper sections 32* consist of outer races within the upper portions of the sockets 31, inner races around the upper ends of the shafts 30', and rollers between the races, and are arranged and constructed so that the shafts 30 are held against downward axial displacement with respect to the brackets 33. The lower sections 32b of the roller bearings consist of outer races within the lower portions of the sockets 31, inner races around the upper ends of the shafts 30 and roller bearings between the inner and outer races and are shaped and constructed, as shown in Figure 2, so that they prevent upward axial displacement of the shafts ,30 with respect to the brackets. The upper ends of the sockets 31 are closed by means of caps 38 which are fixedly secured to the top portions of the brackets. The lower ends of the sockets are closed or protected against the ingress of sand by means of caps 39 which are bolted or otherwise secured to the bottom portions of the brackets and support collars 40. The latter, as shown in Figure 2, extend around the portions of the shafts 30 which are between the roller bearings 32 and the upper portions of the cores 28 of the mulling balls 5. The inner portions of the brackets are tubular in character and fit within forks 4I at the ends of the cross-arm 35. The pins 34 extend through and are journaled in the tubular portions of the brackets and fit within holes in In order to limit outward swinging movement of the shafts 30 and the mulling balls 5, lugs 42 and stop screws 43 are provided. The lugs project upwardly from the inner tubular Y portions of the brackets and then extend inwardly into overhanging relation with respect to the ends of the cross-arms 35. The stop screws 43 extend through the inwardly extending portions of. the lugs and are adapted when brought into abutting relation with the cross-arm to limit outward swinging of the balls. Lock nuts 44 on the upper ends of the screws serve to hold the screws in their various adjusted positions. By adjusting the screws vertically with respect to the lugs 42 the extent of outward swinging of the mulling balls with respect to the side wall of the receptacle may be controlled. By emplo'ying the lugs and stop screws the mulling balls may be controlled so that during drive of the shaft 38 in connection with operation of the mulling apparatus the balls do not swing outwards sufficiently far to strike against the bulged side wall I3 of the receptacle. The shafts 3U are inclined upwardly and outwardly, as shown in Figure 2, when the apparatus is at rest, and the balls are mounted on the shafts so that they are positioned a slight distance above the receptacle V shafts 38 they are free to rotate while they are moved in a circular course within the receptacle. As the result of. rotation of the balls and swinging of the balls in a circular course within the receptacle, the sand is effectively mulled. The solid frubber coverings 29 are spherical and fit over and around the cores 29. By reason of the fact that the covers are formed of solid rubber the sand is yieldingly or elastically gripped for mulling purposes during operation of the apparatus.

By reason of the fact that the shafts 30 are upwardly `and outwardly inclined when the apparatus is at rest the balls, when the apparatusis set into .operationyswing downwards and outarm and forms a driving connection between the shaft and the cross-arm whereby when the wards and then upwards toward the outwardly bulged lower portion of the receptacle `side wall.

VBecause of this `action the sand on the receptacle bottom I2 is urged outwards into the outwardly bulged side wall of the receptacle where it is subjected to the mulling action of the balls I6. As a result of the factthat the balls rotate or spin during travel in their circular course within the l receptacle, the sand on the receptacle bottom I2 as well as the sand within the outwardly `bulged side wall .of the receptacle is subjected to mulling. The upper end of 'the vertically extending .shaft 36 is provided with a polygonal stem 45 and i embodies a shoulde 46 beneath the stem. As shown in Figure 2, t e stem'flts within a polygonal socket 41 in the centralportion of the crossshaft is driven the cross-arm together with the shaft 36 and the mulling' balls 5 is rotated bodily within the receptacle 4. The central portion d! the cross-arm rests on the shoulder 46 and is locked in place by means of a cap 46 which overlies the central portion of the cross-arm and is clamped Vor urged in a downward direction by means of a bolt 49 which extendsthrough the cap 48 and iits within an internally threaded socket in the polygonal stem 45. The upper end of the shaft 36 is journaled in a roller bearing 56' and the lower end of the shaft is supported and journaled in a roller bearing 5I. The bearing 50 consists of an outer race within the `upper end of the upstanding tubular member I4 of the receptacle 4, an inner race around the upper end of. the shaft 26, and an annular series of rollers between the two races. The races and rollers of the bearing 58 are arranged and constructed so as to hold Athe shaft against upward axial displacement with respect to the tubular member I4. The roller bearing 5I is constructed and arranged to hold the shaft 36 against downward axial displacement and consists of anl outer race withina hub-like member 52 on the bottom wall 6` of the frame 3, an inner race around the lower end of the shaft 36 and an annular series of rollers between the two races. The hub-like member 52 is disposed in the rgear compartment 9 and is formed as an integral part of the bottom wall 6 of the frame.

thereof extends through the frame top 9 and into the gear compartment 9 and is journaled in an upper bearing 55 and a lower bearing 56. These two bearings are formed as integral parts of the frame top 8 and the bottom wall 6 respectively. The speed reducing gearing comprises a pinion 5'I, an idler gear 59, a gear 59, a pinion 66, and a gear 6 I The pinion 5'I is flxedly secured to the lower end of the armature shaft of the electric motor 53 and meshes with, and serves to drive the idler gear 58. 'Ihe idler gear is mounted on a vertically extending shaft 62 and meshes with and drives the gear 59. As shown in Figure 2, the shaft 62 is positioned in the gear compartment 9 and is journaled in an upper bearing 63 and a lower bearing 64 which are formed as integral parts of the frame top 6 and the bottom wall 6 respectively. The gear 59 is keyed or otherwise iixedly secured to a vertically extending shaft 65 which is'journaled in or held in axial displacement by an upper roller bearing 66 and a lower bearing 61. The upper bearing is mounted in a socket in the top 8 of the frame 3 and the lower bearing ismounted in a socket in the bottom wall 6 of the frame. l keyed or otherwise fixedly securedto the shaft 65 and is disposed between the gear 59 and the upper roller bearing 66. Thegear 6I is xed to the lower end of the shaft `36 and meshes with The pinion 66 is and is driven by the pinion 66 on the shaft 65. u

When the motor 53' is `supplied with current it operates through the medium of the speed reducing gearing in the gear compartment 9 to drive the shaft 36, which in turn swings or rotates the cross-arm 35, the shafts 36 and the `mulling `balls 5.

In addition to the frame 3, the receptacle 4,

and the mulling balls 5 the apparatus comprises,

tom I2. They are mounted on the outer ends 0f a pair of radially extending angle iron bars 69 and comprise scraping parts` 10 and deflecting parts 1I. Preferably the plows are in the form of plate metal stampings. The scraping parts 'I6 of the` plows are located adjacent to the outwardly bulged side wall `of the receptacle and have the outer edges thereof shaped or curved conformably to the inner periphery of the receptacle side wall. As `shown in Figure 2, the

scraping parts of theplows extend from the bot tom of the receptacle to thefunnel shaped mouth I5 and are curved or rounded so that during op,- eration or drive of the apparatus they scrape the mulled sand from the inner face of the receptacle side wall and direct it toward the deflecting parts 1I. The latter extend inwardly and rearwardly with respect to the lower ends of the scraping parts and overlie the receptacle bottom I2. They project at approximately 45 angles lit with respect to the angle iron bars 69 and operate to deilect the scraped mulled sand toward the central portion of the receptacle bottom. The angle iron bars 69 are attached to a cylin drical skirt l2 on the cross-arm 35 by means of brackets i3. They extend radially with respect to the skirt and are connected to the plows by means of angle brackets M. The skirt to which the brackets 13 are attached is formed as an integral part of, and depends from, the central portion of the cross-arm 35 and surrounds the upper end of the tubular member lll of the receptacle l. The plows operate because of the specific shaping of the scraping and deflecting parts to roll or tumble the mulled sand inwards onto the central portion of the receptacle body and effect aeration of the sand as Well as a secondary mulling action.

In order to cause the sand on the central or inner portion of the bottom I2 of the receptacle to move outwards by centrifugal force into the path of the mulling balls 5 mechanism is pro vided for rotating the receptacle conjointly with the cross arm 35. This mechanism is in the form of gearing between the electric motor 53 and the lower end of the tubular member ill of the receptacle l and consists of a pinion l5, an idler gear it and a gear ll. The pinion 'i5 is fixed to the lower end of the armature shaft of the motor and is located above the top 8 of the frame il. The idler gear 16 meshes with and is driven by the pinion l5 and is loosely mounted on the upper end of the shaft 62. The gear 'll is keyed or otherwise fixedly secured to the lower end of the tubular member Hl of the sand receiving receptacle and meshes with and is driven by the idler lt. lt is disposed above the top ii, of the frame and is jammed or locked against the receptacle bottom l2 by the inner race 2l of the roller bearing iii. rIhe idler gear 16, like the pinion 'l5 and the gear ll, is located above the frame top A sheet metal guard lil overlies the pinion 'l5 and the gears 1G and 'il and serves to protect the gearing against sand. This guard is supported in any suitable manner and is provided with a downwardly and outwardly extending skirt 'lil for deecting downwards and around the frame 3 any sand which drops upon it. When the motor 53 is operated tl'e gearing between the armature shaft and the shaft 3G operates to drive the cross-arm 35 and the balls 5 in one direction and the gearing between the armature shaft and the lower end of the tubular member operates to drive the receptacle in `the reverse or opposite direction. If it is desired to drive the receptacle in the same direction as the mu11- ing balls but at a lower speed the idler gear 'i6 may be dispensed with and a larger gear may be substituted for the gear l'l.

When it is desired to mull sand -with the apparatus the sand to be mulled is shoveled or otherwise delivered into the mouth. l5 of the receptacle Il. When striking the mouth the sand is deflected or directed into the central portion of the receptacle. When the electric motor 53 is started by supplying it with electric current the 4shaft 3S is driven through the medium ot the speed reducing gearing in the gear compartment 9 and in turn drives the cross-arm 35, the shafts Sil and the mulling balls 5. During drive of the cross-arrn the mulling balls move in a circula-r course around the inside of the receptacle and in response to centrifugal force move outwards towards the outwardly bulged side wall i3 of the receptacle and mull the sand between them atrae/is and said receptacle side wall. During drive of the balls around the receptacle the balls spin or rotate and effect not only mulling of the sand within the receptacle side wall but also the sand on the outer portion of the receptacle bottom. The mulled sand, that is the sand which is compressed against the side wall of the receptacle as the result of the action of the mulling balls, is scraped from the inner face of the receptacle side wall by the scraper parts 10 of the plows 68 and is deected inwards onto the inner portion of the bottom I2 of the receptacle as the result of the action of the deector parts 1I of the plows. As soon as the sand is deected inwards onto the central portion of the receptacle bottom itis subjected to the action of centrifugal force resulting from rotation of the receptacle and is flung outwards onto the outer portion of the receptacle bottom and against the inner face of the outwardly bulged side wall I3 wherein it is disposed in the path of travel of the balls and is again subject to a mulling action. As the result of com pression by the balls and also the action of the plows an effective and efficient mulling of the sand occurs. When the sand is mulled to the proper or desired extent the motor is stopped and the sand is removed in any suitable manner from the receptacle. Due to the fact that provision is made for rotating the receptacle deectors for moving the sand outwards into the path of the mulling balls are unnecessary. Furthermore the effect of mulling is obtained without the necessity of having to drive the cross-arm and the mulling balls at an extremely high speed.

The herein described mulling apparatus is not only efncient in operation but may be manufactured at a low and reasonable cost due to sim plicity of design and construction.

Although the apparatus has been described as being adapted primarily for use in a foundry in connection with mulling, mixing or reconditioning molding sand, it is to be understood that the apparatus may also be used to mull or condition materials other than sand and of either plastic or semi-plastic character. The invention is not to be understood as restricted to the details set forth since these may be modified within the scope of the appended claims, without departing from the spirit and scope of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent is:

1. In a mulling apparatus of the character described, the combination of a frame, an open top receptacle for the material to be mulled mounted on the frame to revolve about a vertical axis and comprising a substantially hat circular bottom and an annular outwardly bulged side wall joined to and extending upwardly from the outer margin of the bottom, a freely rotatableinulling ball arranged toctravel in a circular course around the side wall of the receptacle and adapted during such travel to spin and effect mulling of the material between it and said side wall, means for propelling the mulling ball in said circular course, a scraper type plow located behind and connected for conjoint propulsion with the ball and having a part shaped conformably to the inner face of the outwardly bulged side wall and adapted to scrape the mulled material from the latter and having another part positioned to direct the scraped material inwardly onto the receptacle bottom, and means for rotating the receptacle at such a speed that the material scraped by the plow and directed inwardly onto the receptacle bottom is flung outwards by centrifugal force toward the-side wall into the course of travel of the ball." l i 2. lIn a mullingapparatus of the character described, the combination of a frame, an open top receptacle for the material to be mulled mounted to travel in one direction in a circular course over the outer margin of the bottom and around the side wall and adapted during such travel to spin and effect mulling of the material between it and said side wall, means for propelling ,the ball in said circular course, an angularly disposed scraper type plow located behind and connected for conjoint propulsion with the `"ball and having a part shaped conformably tothe inner face of the outwardly bulged side wall and adapted to scrape the mulled material from the latter and having another part positi `ned todirect the scraped material inwardly onto the receptacle bottom, and means for rotating the receptacle in the opposite `direction at such speed that the scraped and inwardly directed material on the `central portion'of the bottom is flung outwards by centrifugal force towards the side wall into the course of travel of the ball.

3. In a mulling apparatus of the character described, the combinationpf a frame; an open top receptacle for .thematerial to be mulled positioned above the frame and comprising a substantially flat circular bottom, a centrally disposed upstandingf" tubular member extendingl to spin and effect mulling o'f the material between it and said side wall; means for propelllng the mulling element in saidcircular course comprising a vertical power driven shaft extending through `the tubular member of the receptacle and a cross arm fixed to rotate with, and projecting outwardly from the'upper end of, the shaft and provided with element propelling l means at its outer end; and means applied to said lowerend of the tubular member of the receptacle for rotating the receptacle at such speed that the material on the central portion thereof is flung outwards `by centrifugal force towards the side wall into a position wherein it is in the course of travel of the element.

4. In a mulling apparatus of the character described, the combination of a frame,` an open top receptacle for the material to be mulled mounted on the frame to revolve about a vertical axis and comprising a substantially flat circular bottom and an annular outwardly bulged side wall joined to and extending upwardly from the outer margin of the bottom, a freely rotatable mulling ball disposed over the outer `margin of the receptacle bottom adjacent to the outwardly bulged side wall and adapted to spin and effect mulling of the material between it and said side wall, a scraper type plow located behind the ball and during rotation of the receptacle and having 'an-1 other part positioned to direct the scraped material inwardly onto the receptaclebottom, and power driven mechanism for rotating the receptacle so as to cause the material on the central portion of the receptacle bottom to be flung outwards by centrifugal force toward the side wall for contact with the mulling ball for mulling purposes'.

5. In a mulling apparatus of the character described, tlie combination of a revolvable open top receptacle adapted to contain the material to be mulled and comprising a substantially fiat circular bottom and an annular side wall joined to and extending upwardly from the outer margin of the bottom, a freely rotatable mulling element arranged to travel in one direction in a circular course over said outer margin of the bottom and around the side wall and adapted during such travel to spin and effect mulling of the material between it and said side wall, means for propelling the ball in said circular course, an angularly disposed scraper type plow located behind and connected for conjoint propulsion with the element and having a part shaped 'conformably to the inner face of the side wall and adapted to scrape the mulled material from the latter and having -another part positioned to direct the scraped `material inwardly onto the receptacle bottom, and means for rotating the receptacle in the opposite direction at such speed that the scraped and [inwardly directedrmaterial on the bottom is flung outwardly by centrifugal force againststhe `receptacle side wall into the course of travel of the element. l

6. In a mulling apparatus of the character described, the combination of a revolvable open topreceptacle adapted to contain the material to be mulled and comprising a substantially fiat circular bottom and an annular side wall joined to and extending upwardly from the outer margin of the bottom, a freely rotatable mulling element arranged to travel inone direction in a circular course around the side wall and adapted during such travel to spin and effect mulling of the material between it and said side wall, an electric motor, gearing driven by the motor for propelling the element inV said circular course, a scraper type plow located behind and connected for conjoint populsion with the element and having the leading part shaped conformably and positioned adjacent to the inner face of the side wall so as to scrape the mulled material from the latter and having its trailing part positioned and shaped to direct the scraped material inwardly onto the receptacle bottom, and gearing driven by said motor for rotating the receptacle in the opposite direction and at such a speed that the material on the bottom thereof is flung outwards by centrifugal force against' the side wall into a position wherein it is in the course of travel of the element.

'1. In a mulling apparatus of the character described, the combination of a frame;4 an open top receptacle for the material to bemulled positioned above the frame and comprising a substantially flat circular bottom, an upstanding tubular member extending through the central portion of the bottom and having the lower end thereof journaled in bearings in the frame so 'that the receptacle is revolvable about a sub. `stantially vertical axis, and an outwardly bulged side wall joined to and extending upwardly from the marginof the bottom; a freely rotatable mulling ball arranged to travel in one direction in a circular course around the side wall of the receptacle and adapted during such travel to spin and effect mulling of the material between it and said side wall; means for propelling the mulling ball in said circular course comprising an electric motor, a vertical shaft extending through the tubular Vmember and gearing between the motor and the lower end of the shaft; and means for rotating the receptacle in the opposite direction and at such speed that the material on the bottom thereof is iiung outwards by centrifugal force towards the side wall and into the course of travel of the ball, comprising gearing between said motor and said lower end of the tubular member.

WALTER F. PIPER. 

